Abstract: Methods of measuring biometric characteristics using a sensor positioned in an ear canal of a user are provided. The sensor is positioned on or connected to an ear tip, a contact hearing device, or one or more components thereof. One or more biometric signals may be sensed from the sensor. The biometric characteristic of the user is measured or derived from these sensed signals, and include but are not limited to the temperature of the user, acoustic signal(s) from the user, movement(s) of the user, a ballistocardiogram, an electrocardiogram, oxygen saturation, and blood pressure.